1. Field of the Invention
New, improved antibiotics are continually in demand. In addition to antibiotics which are useful for human diseases, improved antibiotics are also needed in the veterinary field.
Coccidiosis is one disease important to veterinary science, especially to the poultry industry. Coccidiosis results from infection by one or more species of Eimeria or Isopora (for a summary see Lund and Farr in "Diseases of Poultry," 5th ed., Biester and Schwarte, Eds., Iowa State University Press, Ames, Iowa, 1965, pp 1056-1096). Economic losses due to coccidiosis are great, and known anticoccidial agents have many disadvantages. Improved anticoccidial agents continue to be needed.
2. The Prior Art
A-32887 is a polyether antibiotic. At the time application Ser. No. 801,876 was filed, A-32887 was thought to be closely related to, but different from, the prior art antibiotic K-41 [J. Antibiotics 29 (1), 10-14 (1976)]. Subsequently, however, it has been determined that A-32887 is identical to K-41. A-32887 (K-41) has the following structure: ##STR1##
K-41 was known to be useful as a Grampositive antibiotic. The fact that K-41 is useful for the treatment of coccidiosis in poultry, however, was not previously recognized.